Our official SolderSmoke etymologist and lexicographer Steve Silverman explains:
Here is some ham radio/electronics trivia
In the days when amateur radio used short range spark transmitters, multi-station relays were used to move a message across longer distances. At the end of each transmission, a "K" was sent, which told the receiving operator to commence his relay to the next station. Hence the use of 'K" to designate a relay in a schematic diagram, and "end-of-transmission" for CW operators. And hence the American Radio RELAY League
KB3SII ... .. ..
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